

// Do this as the first thing so that any code reading it knows the right env.
process.env.BABEL_ENV = "production"
process.env.NODE_ENV = "production"

// Makes the script crash on unhandled rejections instead of silently
// ignoring them. In the future, promise rejections that are not handled will
// terminate the Node.js process with a non-zero exit code.
process.on("unhandledRejection", err => {
    throw err
})

// Ensure environment variables are read.
require("../config/env")

const path = require('path');
const chalk = require('chalk');
const fs = require('fs-extra');
const webpack = require('webpack');
const config = require('../config/webpack.config.prod');
const paths = require('../config/paths');
const checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
const formatWebpackMessages = require('react-dev-utils/formatWebpackMessages');
const printHostingInstructions = require('react-dev-utils/printHostingInstructions');
const FileSizeReporter = require('react-dev-utils/FileSizeReporter');
const printBuildError = require('react-dev-utils/printBuildError');

const measureFileSizesBeforeBuild = FileSizeReporter.measureFileSizesBeforeBuild
const printFileSizesAfterBuild = FileSizeReporter.printFileSizesAfterBuild
const useYarn = fs.existsSync(paths.yarnLockFile)

// These sizes are pretty large. We'll warn for bundles exceeding them.
const WARN_AFTER_BUNDLE_GZIP_SIZE = 512 * 1024
const WARN_AFTER_CHUNK_GZIP_SIZE = 1024 * 1024

// Warn and crash if required files are missing
if (!checkRequiredFiles([paths.appHtml, paths.appIndexJs])) {
    process.exit(1)
}

// First, read the current file sizes in build directory.
// This lets us display how much they changed later.
measureFileSizesBeforeBuild(paths.appBuild)
    .then(previousFileSizes => {
        // Remove all content but keep the directory so that
        // if you're in it, you don't end up in Trash
        fs.emptyDirSync(paths.appBuild)
        // Merge with the public folder
        copyPublicFolder()
        // Start the webpack build
        return build(previousFileSizes)
    })
    .then(
        ({ stats, previousFileSizes, warnings }) => {
            if (warnings.length) {
                console.log(chalk.yellow("Compiled with warnings.\n"))
                console.log(warnings.join("\n\n"))
                console.log(
                    "\nSearch for the " +
                        chalk.underline(chalk.yellow("keywords")) +
                        " to learn more about each warning."
                )
                console.log("To ignore, add " + chalk.cyan("// eslint-disable-next-line") + " to the line before.\n")
            } else {
                console.log(chalk.green("Compiled successfully.\n"))
            }

            console.log("File sizes after gzip:\n")
            printFileSizesAfterBuild(
                stats,
                previousFileSizes,
                paths.appBuild,
                WARN_AFTER_BUNDLE_GZIP_SIZE,
                WARN_AFTER_CHUNK_GZIP_SIZE
            )
            console.log()

      const appPackage = require(paths.appPackageJson);
      const publicUrl = paths.publicUrl;
      const publicPath = config.output.publicPath;
      const buildFolder = path.relative(process.cwd(), paths.appBuild);
      printHostingInstructions(
        appPackage,
        publicUrl,
        publicPath,
        buildFolder,
        useYarn
      );
    },
    err => {
      console.log(chalk.red('Failed to compile.\n'));
      printBuildError(err);
      process.exit(1);
    }
  );

// Create the production build and print the deployment instructions.
function build(previousFileSizes) {
    console.log("Creating an optimized production build...")

  let compiler = webpack(config);
  return new Promise((resolve, reject) => {
    compiler.run((err, stats) => {
      if (err) {
        return reject(err);
      }
      const messages = formatWebpackMessages(stats.toJson({}, true));
      if (messages.errors.length) {
        // Only keep the first error. Others are often indicative
        // of the same problem, but confuse the reader with noise.
        if (messages.errors.length > 1) {
          messages.errors.length = 1;
        }
        return reject(new Error(messages.errors.join('\n\n')));
      }
      if (
        process.env.CI &&
        (typeof process.env.CI !== 'string' ||
          process.env.CI.toLowerCase() !== 'false') &&
        messages.warnings.length
      ) {
        console.log(
          chalk.yellow(
            '\nTreating warnings as errors because process.env.CI = true.\n' +
              'Most CI servers set it automatically.\n'
          )
        );
        return reject(new Error(messages.warnings.join('\n\n')));
      }
      return resolve({
        stats,
        previousFileSizes,
        warnings: messages.warnings,
      });
    });
  });
}

function copyPublicFolder() {
    fs.copySync(paths.appPublic, paths.appBuild, {
        dereference: true,
        filter: file => file !== paths.appHtml
    })
}
